Double slit experiment: through which slit did the particle go?

Tomislav P. Živković
Institute Ruđer Bošković, Zagreb

Double slit experiment demonstrates a paradoxical nature of quantum behavior as interpreted within a classical notion of space: a solid particle going simultaneously through two separate slits. A standard formulation of quantum theory provides an exact mathematical prediction of the resulting interference pattern behind those slits. However, this formulation is ultimately unable to provide a satisfactory interpretation of this effect since in a classical picture no solid particle can be simultaneously situated at two different positions in space. From a point of view of a quantum notion of space this effect is explained in a most natural way. In one reference frame this particle is delocalized and it is going simultaneously through those two separate slits. However, there is another (non-classical) reference frame in which the particle is relatively well localized while those two slits are delocalized and they partially overlap each other. Both reference frames are equivalent and the laws of physics are the same in those reference frames. In one reference frame the particle is delocalized while the slits are localized, while in another reference frame the particle is localized while those two slits are delocalized. The existence of such non-classical reference frames requires a substantial modification of a standard notion of space. The same applies to a standard notion of time.